Middleware for ExpressJS to validate the request data against a schema using Mongoose.

example.js

const express = require('express')

const Article = require('./article.model.js')
const validate = require('./validate.middleware.js')
const router = express.Router()

router.get('/articles', 
  validate('query', {
    title: String,
    text: String,
  }),
  (req, res, next) => {
    Article.find(req.query)
      .then(result => res.json(result))
      .catch(error => next(error))
  })

router.patch('/articles/:id', 
  validate('body', {
    title: String,
    text: String,
  }),
  (req, res, next) => {
    Article.create(req.body)
      .then(result => res.json(result))
      .catch(error => next(error))
  })

module.exports = router

validate.middleware.js

const mongoose = require('mongoose')

/**
 * Validates the request data against a schema using Mongoose.
 * @param {string} type - The type of data to validate (e.g., 'body', 'params', 'query').
 * @param {object} rawSchema - The raw schema object to validate against.
 * @param {Object} options - Additional options for validation (default: {}).
 * @returns {Function} - Middleware function to validate the data.
 */
function validate (type, rawSchema) {
  const schema = new mongoose.Schema(rawSchema, {
    _id: false,
    autoCreate: false,
    versionKey: false,
    timestamps: false,
  })
  const Model = mongoose.model('validate-' + Date.now(), schema)

  // Middleware function to validate the request data.
  return function (req, res, next) {
    const rawData = req[type]
    const model = new Model(rawData)
    const error = model.validateSync()

    if (error) {
      res.status(400).json(error)
      return
    }

    // Update request property
    req[type] = model
    next()
  }
}

module.exports = validate